EP0657994A1 - Circuit oscillateur oscillant également avec une tension d'alimentation basse - Google Patents

Circuit oscillateur oscillant également avec une tension d'alimentation basse Download PDF

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Publication number
EP0657994A1
EP0657994A1 EP94119344A EP94119344A EP0657994A1 EP 0657994 A1 EP0657994 A1 EP 0657994A1 EP 94119344 A EP94119344 A EP 94119344A EP 94119344 A EP94119344 A EP 94119344A EP 0657994 A1 EP0657994 A1 EP 0657994A1
Authority
EP
European Patent Office
Prior art keywords
inverter
power supply
voltage
mosfet
vdd
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94119344A
Other languages
German (de)
English (en)
Inventor
Toshihide C/O Nec Corporation Tsuboi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Publication of EP0657994A1 publication Critical patent/EP0657994A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L3/00—Starting of generators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
    • H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
    • H03B5/364—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device the amplifier comprising field effect transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/353—Generators characterised by the type of circuit or by the means used for producing pulses by the use, as active elements, of field-effect transistors with internal or external positive feedback
    • H03K3/354—Astable circuits
    • H03K3/3545—Stabilisation of output, e.g. using crystal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
    • H03B2200/0002—Types of oscillators
    • H03B2200/0012—Pierce oscillator

Definitions

  • This invention relates to an oscillation circuit and, more particularly, to an oscillation circuit that may be set into oscillation at a low voltage.
  • an oscillator employing a quartz oscillator in a semiconductor integrated circuit of the CMOS structure is arranged as shown in Fig.4.
  • a resistor 504 and a quartz oscillator 505 are connected in parallel to each other across the input and the output of the inverter, and capacitors 506, 507 are provided across both terminals of the quartz oscillator 505 and the ground.
  • resistor 504 and the capacitors 506, 507 are occasionally formed on a semiconductor integrated circuit, they are shown herein as being provided externally of the semiconductor integrated circuit, because such is not essential to the description of the present invention.
  • the inverter formed on the semiconductor integrated circuit operates as an amplifier, while the capacitors 506, 507 and the quartz oscillator 505 operate as a frequency filter, so that the components shown operate as an oscillator in their entirety.
  • Vdd a power supply voltage
  • VTN a threshold voltage at which the n-type MOSFET 502 begins to be conductive
  • VTP a threshold voltage at which the p-type MOSFET 502 begins to be conductive
  • the threshold voltage of a MOSFET is associated with the gate-to-source voltage at which the MOSFET begins to turn on such that the threshold voltage VTP of the p-type (enhancement) MOSFET is dealt with as a negative value, while the threshold voltage VTN of the n-type (enhancement) MOSFET is of a positive value .
  • the p-type MOSFET 501 is in a conductive state, while the n-type MOSFET 502 is in a non-conductive state, so that a Vdd level is outputted at an output terminal 511 of the inverter.
  • the p-type MOSFET 501 is in a non-conductive state and the n-type MOSFET 502 is in a conductive state, so that a zero level is outputted at the output terminal 511 of the inverter.
  • both the p-type MOSFET 501 and the n-type MOSFET 502 are in the conductive state and exhibit characteristics in which, the higher the input voltage, the lower becomes the output voltage, as shown in Fig.5.
  • these MOSFETs operate as an inverting amplifier having a certain gain in the region wherein the input voltage and the output voltage are approximately equal to each other.
  • the inverter input is biased by the resistor 504 so that the inverter input voltage becomes equal to the inverter output voltage. After lapse of several msec to several sec in this state, minute oscillations present at the inverter input are amplified, resulting in a growth of the oscillations to produce an oscillation output.
  • Fig.6 shows a graph of input/output characteristics of the inverter made up of complementary MOSFETs for the lower power supply voltage Vdd as defined in the above expression (2), wherein the threshold voltage of n-type MOSFET VTN is larger than Vdd -
  • the input voltage to the inverter is in a range from 0 to Vdd -
  • the p-type MOSFET 501 is in a non-conducting state, while the n-type MOSFET 502 is in a conducting state, so that the inverter outputs the zero level.
  • both the p-type MOSFET 501 and the n-type MOSFET 502 are in the non-conducting state, with the inverter output being is a high-impedance state.
  • the power supply voltage Vdd is set lower than the sum of the threshold voltage levels of VTN and VTP, there is no input voltage range in the inverter capable of amplifying the minute oscillations. Thus there occurs no growth of the oscillations in the present example, such that no oscillation output signal can be produced.
  • the minimum oscillation voltage may indeed be lowered in this manner.
  • the current flowing through such oscillator depends on VTN and VTP, as shown in Fig.7.
  • such inconvenience arises that, if the power supply voltage is raised, the power supply current is increased.
  • VTN and VTP of the semiconductor integrated circuit in its entirety are lowered, data retention characteristics are disadvantageously deteriorated, while the current flowing through the circuit in its entirety is also disadvantageously increased.
  • the production process tends to be complex, thus entailing disadvantages in the term of production and production cost.
  • the JP Patent Publication No. Hei 2-222307 (1990) discloses a technique of changing over the MOSFETs operating as an oscillator amplifier between the high power supply voltage and the low power supply voltage for reducing the power supply current during the time of a high power supply voltage.
  • this technique not only the circuit becomes complex, but also the minimum oscillation voltage essentially depends on VTN and VTP, so that, for producing a low oscillation voltage, it becomes necessary to lower one threshold voltage of VTN and VTP of the MOSFETs constituting the above-mentioned oscillator.
  • the threshold voltage of the inverter operating as the oscillator amplifier may be changed slightly, at the time of changing over MOSFETs, as a result of which there may be generated a noise to be included in the oscillation output signal.
  • the conventional semiconductor integrated circuit suffers from the drawback that, if Vdd is lower than the sum of the voltage levels VTN and VTP, the oscillation output cannot be produced using a quartz oscillator.
  • An oscillator circuit according to the present invention is characterized by connecting a resistive element between an output of an inverter and a power supply terminal.
  • the output of the inverter is pulled up to the level of the source voltage by the resistive element, so that there is no risk of the inverter output being in a high-impedance state.
  • the inverter cooperates with the resistive element to serve an inverting amplifier having a certain gain.
  • the inverter may perpetually be set into oscillation without regard to the power supply voltage or to the MOSFET threshold voltage.
  • an oscillation circuit 100 includes an inverter 110 made up of a p-type or p-channel insulated-gate field effect transistor (called hereinafter MOSFET) 101 and an n-type or n-channel MOSFET 102 connected in series between a power terminal Vdd and a ground terminal.
  • MOSFET insulated-gate field effect transistor
  • a resistor 104 and a resonant element 105 such as quartz are connected in parallel between the input and the output of the inverter 110, and capacitors 106 and 107 are connected between both terminals of the quartz oscillator 105 and the ground, respectively.
  • the input of the inverter 110 is connected to an input terminal 108, and the output thereof is connected to an output terminal 111.
  • the present oscillation circuit 110 further includes a resistor 103 in accordance with the present invention.
  • This resistor 103 is connected between the power supply Vdd and the drain of the p-type MOSFET 101 operates as an amplifier, while the capacitors 106, 107 and the quartz oscillator 105 operate as a frequency filter, such that the circuit 100 in its entirety operates as an oscillator.
  • the inverter 110 and the resistor 103 are fabricated on a single semiconductor chip. Although the resistor 104 and the capacitors 106 and 107 are shown as being provided outside of the semiconductor integrated circuit, they may be also fabricated on the semiconductor chip.
  • the p-type MOSFET 101 is in a conducting state, while the n-type MOSFET 102 is in a non-conducting state, so that the Vdd level is outputted as the output voltage V O at the output terminal 111, as shown in Fig. 2.
  • the p-type MOSFET 101 is in a non-conducting state, while the n-type MOSFET 102 is in the conducting state, so that the output voltage V O takes a zero level, as shown in Fig. 2.
  • both the p-type MOSFET 101 and the n-type MOSFET 102 are in the non-conducting state.
  • the voltage level V O at the output terminal 111 is thereby pulled up to the Vdd level by the resistor 103, as shown in Fig. 2. Consequently, with the present embodiment, the circuit made up of the p-type MOSFET 101, the n-type MOSFET 102 and the resistor 103 operate as an inverting amplifier having a certain gain within a range of the input voltage approximately being equal to VTN.
  • the circuit made up of the p-type MOSFET 101, n-type MOSFET 102 and the resistor 103 is biased so as to have an amplification factor, so that minute oscillations present in the inverter input are amplified and grown in amplitude to produce an oscillation output.
  • the device dimension parameters of MOSFETs and element values are as follows. channel width of the p-type MOSFETs 101,501 ⁇ 16 ⁇ m channel length of the p-type MOSFETs 101,501 ⁇ 12 ⁇ m channel width of the n-type MOSFETs 102,502 ⁇ 8 ⁇ m channel length of the n-type MOSFETs 102,502 ⁇ 12 ⁇ m gate oxide film thickness of MOSFETs 101,102,501, 502 ⁇ 280 ⁇ m resistance value of resistor 103 ⁇ 50K ⁇ resistance values of resistors 104,504 ⁇ 5M ⁇ capacitance values of capacitors 106,107,506,507 ⁇ 15pF Table 1 Threshold voltage level Oscillation start voltage with the conventional circuit Oscillation start voltage by the present invention Vt level 1 1.26 V 1.26 V Vt level 2 1.54 V 1.40 V Vt level 3 1.68 V 1.23 V Vt level 4 1.75 V 1.40 V Vt level 5 2.02 V 1.42 V
  • Vt levels 1 to 4 indicate the ranks of MOSFET threshold voltage levels VTN and VTP in an ascending order.
  • Vt level 1 denotes a group of MOSFETs that are manufactured to have lowest threshold voltage values of both VTN and VTP
  • Vt level 5 denotes a group of MOSFETs having highest threshold voltage values of both VTN and VTP.
  • the oscillation start voltage indicates the minimum value of the power supply voltage Vdd at which the oscillation can be started.
  • an oscillation circuit 400 includes, in place of the resistor 103 of the embodiment 1 shown in Fig.1, an n-type normally-on MOSFET 403.
  • the arrangement of a p-type MOSFET 401, an n-type MOSFET 402, a resistor 404, a quartz oscillator 405, capacitors 406, 407, an input terminal 408 and an output terminal 409 are similar to that of the p-type MOSFET 101, n-type MOSFET 102, resistor 104, quartz oscillator 105, capacitors 106, 107, input terminal 108 and the output terminal 109, shown in Fig.1, so that the corresponding description is not made.
  • the n-type normally-on MOSFET 403 has its drain connected to a power supply Vdd, while having its source connected to the output terminal and having its gate grounded.
  • the present embodiment since the gate-to-drain voltage of the n-type normally-on MOSFET 403 is negative and the absolute value thereof is increased with rise in Vdd, the on-resistance is increased.
  • the present embodiment has the effect that, as compared to the first embodiment, the current flowing through the oscillator becomes smaller for a larger value of Vdd.
  • a depletion type MOSFET may be employed in place of the resistor 103 and the MOSFET 403.
  • the feedback resistor 104 or 404 can be replaced with a pair of n-channel and p-channel MOSFETs whose gates are connected to the ground and the power supply terminal, respectively.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
  • Logic Circuits (AREA)
EP94119344A 1993-12-07 1994-12-07 Circuit oscillateur oscillant également avec une tension d'alimentation basse Withdrawn EP0657994A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP5306847A JPH07162237A (ja) 1993-12-07 1993-12-07 発振回路
JP306847/93 1993-12-07

Publications (1)

Publication Number Publication Date
EP0657994A1 true EP0657994A1 (fr) 1995-06-14

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Family Applications (1)

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EP94119344A Withdrawn EP0657994A1 (fr) 1993-12-07 1994-12-07 Circuit oscillateur oscillant également avec une tension d'alimentation basse

Country Status (3)

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EP (1) EP0657994A1 (fr)
JP (1) JPH07162237A (fr)
KR (1) KR950022037A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0838898A1 (fr) * 1996-10-28 1998-04-29 Oki Electric Industry Co., Ltd. Circuit oscillateur à deux modes
EP1111770A1 (fr) * 1999-12-21 2001-06-27 Eta SA Fabriques d'Ebauches Dispositif oscillateur à quartz basse fréquence ayant un comportement thermique amélioré
GB2360154A (en) * 2000-03-09 2001-09-12 Texas Instruments Ltd An IGFET oscillator operable on a low supply voltage
US6509804B2 (en) 1999-12-21 2003-01-21 Eta Sa Fabriques D'ebauches Low frequency quartz oscillator device with improved thermal characteristics

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100347950C (zh) * 2002-12-04 2007-11-07 联华电子股份有限公司 包含有一动作模组以提升负电阻值的栓锁器系统
KR101360468B1 (ko) * 2007-07-20 2014-02-07 엘지이노텍 주식회사 발진회로
JP2012034079A (ja) * 2010-07-29 2012-02-16 Fuji Electric Co Ltd 絶縁ゲート型デバイスの駆動回路

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3889211A (en) * 1972-08-28 1975-06-10 Suwa Seikosha Kk MOS field effect transistor crystal oscillator
US3979698A (en) * 1973-10-19 1976-09-07 Itt Industries, Inc. Crystal oscillator circuit
JPH04208701A (ja) * 1990-12-03 1992-07-30 Toyo Commun Equip Co Ltd 発振器の動作安定化方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1022942B (it) * 1973-10-19 1978-04-20 Itt Circuito oscillatore a cristallo
JPS5655482A (en) * 1979-10-15 1981-05-16 Onoda Cement Co Ltd Rapid-curing grouting material
JPH0677731A (ja) * 1992-05-12 1994-03-18 Nippon Precision Circuits Kk 発振制御回路および発振回路
JPH06204741A (ja) * 1992-12-28 1994-07-22 Fujitsu Ltd 発振回路

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3889211A (en) * 1972-08-28 1975-06-10 Suwa Seikosha Kk MOS field effect transistor crystal oscillator
US3979698A (en) * 1973-10-19 1976-09-07 Itt Industries, Inc. Crystal oscillator circuit
JPH04208701A (ja) * 1990-12-03 1992-07-30 Toyo Commun Equip Co Ltd 発振器の動作安定化方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 16, no. 550 (E - 1292) 19 November 1992 (1992-11-19) *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0838898A1 (fr) * 1996-10-28 1998-04-29 Oki Electric Industry Co., Ltd. Circuit oscillateur à deux modes
US5900787A (en) * 1996-10-28 1999-05-04 Oki Electric Industry Co., Ltd. Dual-mode, crystal resonator/external clock, oscillator circuit
EP1111770A1 (fr) * 1999-12-21 2001-06-27 Eta SA Fabriques d'Ebauches Dispositif oscillateur à quartz basse fréquence ayant un comportement thermique amélioré
US6509804B2 (en) 1999-12-21 2003-01-21 Eta Sa Fabriques D'ebauches Low frequency quartz oscillator device with improved thermal characteristics
GB2360154A (en) * 2000-03-09 2001-09-12 Texas Instruments Ltd An IGFET oscillator operable on a low supply voltage

Also Published As

Publication number Publication date
JPH07162237A (ja) 1995-06-23
KR950022037A (ko) 1995-07-26

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